Yueh-Ning Lee

(National Taiwan Normal University)

The nature of turbulence in molecular clouds is one of the driving factors that influence star formation efficiency. It is speculated that the high star formation efficiency observed in spiral-arm clouds is linked to the prevalence of compressive (curl-free) turbulent modes, while the shear-driven solenoidal (divergence-free) modes appear to be the main cause of the low star formation efficiency that characterizes clouds in the Central Molecular Zone (CMZ). Similarly, the anal- ysis of the Orion B molecular cloud confirmed that the dominant solenoidal turbulence is compatible with its low star formation rate. However, turbulence modes also vary locally and at different scales within a cloud, and turbulent motions surrounding the main star-forming regions display a strongly compres- sive nature. This evidence points to inter-and intra-cloud fluctuations of the solenoidal modes being an agent for the variability of star formation efficiency and cloud collision being a facilitator of stars’ formation through the production of highly compressive gas flows.

The goal of this project is to obtain a quantitative estimation of the fraction of solenoidal and compressive modes across molecular clouds with varying features, and to compare them to the star-formation efficiency, derived independently. We will focus on a sample of clouds in three representative Galactic environments (the CMZ, the Inner and Outer Galaxy) to probe how the environment impacts star formation.

This project will be co-supervised by Raffaele Rani.